Horn antennas, also known as microwave horns, include a flaring metal waveguide shaped like horn that directs radio waves in a beam. Horn antennas have multiple uses, including small-aperture antennas to feed reflectors to large-aperture antennas used by themselves as medium-gain antennas.
The performance of horn antennas is based on the shape and size of the horn. When designing the horn antenna, other considerations are taken into account, such as the fluctuation in temperature, humidity, dust and impurities in the surrounding air and other related factors. These factors affect the propagation of the signals. Therefore, to achieve a better signal, the antenna is designed to provide high gain. High gain generally implies that the antenna size is large. In some examples, size requirements prevent designing the antenna according to the needed size to achieve the required gain. In such instances, other adjustments to the design are considered.